Ship&#39;s hull having forked canal in bottom



Jan. 3, 1956 G. B. TOMMASI 2,7

SHIPS HULL HAVING FORKED CANAL IN BOTTOM Filed May 28, 1951 5 Sheets-Sheet 1 I 11 0 emtev,

Jan. 3, 1956 e. B. TOMMASI 2,72

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' SHIP'S HULL HAVING FORKED CANAL IN BOTTOM Filed May 28, 1951 5 Sheets-Sheet 5 INVENTOR. GIOVANNI B. TOMMASI WM, 224 m Att s.

United States Patent 2,729,182 SHIPS HULL HAVINGFORKED CANAL 1N BOTTOM Giovanni Bl Tommasi l iome, ltaly Application May 28, 1951,'Serial No. 228,642 Claims priority, application Italy June 3', 1950 V 14 Claims. (c1. int-51 V The present invention relates to improvements in the shape of the bottom of screw propelled ships intended to increase the propulsion efficiency of the combined screw-hull, owing to the particular shape given to the ships bottom. e V

It is known to increase the propulsion efficiency of a propeller by coaxially disposing two propellers rotating in opposite direction or else to locate fins before the propeller which impart to the water flow entering the disc of the propeller a pitch such as would be generated by a co-axial propeller. p p e For increasing the propulsion efliciency of the propeller and for making them similar to those of the propellers of turbo-compressors and turbo-pumps, heretofore in the naval art there have been added to the usual type of hulls canals, fins or casing for the shaft of the propellers. v 7

It is an object of the present invention to increase the propulsion efiiciency of the propeller through a radical alternation of the usual shape of the stern portion of the hull, assuming that stem propellers are used. The bow portion of the hull is kept unaltered.

The present invention consists in a ships hull which comprises at least one main central canal formed lengthwise in the bottom of the hull beginning from the midship, the said canal having a pa'rt-circularsection which increases continuously in depth toward the stern until it forks to provide two canals each of which has an end portion with a helicoidal shape ending at the hub of a propeller rotating in a direction opposite to the final direction of the canal, a mantle being provided in continuance of the canal beyond the said propeller toward the stem. The canals will be hereinafter indicated as helicoidal canals.

The central canal and the two helicoidal diverging canals generate in the bottom of the hull two torpedo shaped bodies which contain the shaft of the propellers. The shaft of each propeller isinclined with respect to the axis of. the torpedo shaped body, both laterally and in a vertical plane, so that the plane containing the shaft of the propeller and the axis of the torpedo shaped body shaft of the propeller lies. The said bodies merge into the usual shape of the bow portion of the hull and at their stern extremities supporting th e propeller project from the helicoidal canal. The wa l l of the helicoidal canal ends at the hub of the propeller iii the fo'rrn of a blade inclined with respect to the direction of the motion, said inclination being equal to the inclination of the stream of water entering the disc of the propeller.

Between the two helicoidal canals a bulge maybe provided to separate the stream of water entering the said canals.

It is not necessary that the two mantles formed in continuance of the helicoidal canals at the propeller have their wall completed along the whole periphery, since it is s'ufiicient if. it is' de'vlopdrin theportion of the intersects the helicoidal canal on the side wherein the wall formed by the plating of the bottdm of the stern 2 of the hull. Thisconstrnction is advisable for lightening purpose.

The stream of water entering the disc of the propeller and having a rotating direction corresponding to that of the helicoidal canal reverses its direction in passing through the propeller. For the best efficiency of the propulsion, the pitch of the propeller must be so designed that the pitch of the stream of water leaving the propeller lies between one half and twice the pitch of the stream of water before it enters the propeller.

In the stern portion of the torpedo shaped bodies, fins may be provided projecting from the said bodies and inclined with respect to the longitudinal axis of the hull, for the purpose of equating the transverse component of the speed of the water stream flowing along the outer side of the hull and the transversal component of the water stream coming from the canal.

The invention will be more fully understood from the following description of embodiments of the invention taken with the drawings in which:

Fig. 1 is an axonometric view of the stern portion of a hull with a main canal divergent and two screw-propellers;

Figs. 2 to 8 are schematic planes of the square frames of different embodiments of a hull according to the invention, in which planes are indicated only three square frames, namely the main square frame A, the square frame B at the stem end of the helicoidal canals and an end stern square frame C.

.Figs. 9 and 10 are respectively diagrammatical side and plan views of a submarine provided with a canal according to the invention; I

Fig. 11 is a stern end view of the submarine of Figs. 9 and 10. I

Fig. 12 is a diagrammatic view in a plane perpendicular to the axis of the vortex, of the elements comprising the point wherein the water flux coming from the helicoidal canal joins that coming from outside the hull.

Fig. 13 is a bottom view of the ships hull, and

Figs. 14 to 21 inclusive are cross sections taken along the section lines 1414 to 21-21 of Fig. 13.

With reference to the drawings, the keel line of the ships bottom shown in Fig. l is indicated by 1, and the various square frames 2, shown in dotted line,- illustrate their development and the formation of the canal.

In Fig. 1, reference numerals 3 and 4 indicate the casing for the hubs of the propellers, the latter not being shown in the drawing. The shafts of the propellers are mounted in the torpedo shaped bodies F0 and 5'1. 7

The helicoidal canals are indicated by 5 and 6. and 45 indicate the edge in the shape of a blade ending the said blade joins with the outer wall ofthe hull are indicated by 7 and 8.

Between the two helicoidal canals 5 and 6 is provided a bulge 9, whereon the support of the central rudder 10, in the example shown, is placed.

46 and 47 indicate the edge formed by the wall of the stern plating and the wall of the mantle 4S and 49.

11 and 12 indicate .fins applied to the torpedo shaped bodies and inclined with respect to the axis of the said bodies. p e

The Figs. 2 to 8 show the arrangement of the screws and of the helicoidal canals in the different cases of application of this invention.

In said figures are shown the sections of the ship corresponding: tothe central square frame, to the square frame where the fluxes external and internal to the canal unite before the screw disc, and to a theoric stern square frame. V p e In a ship with two screws shown in Fig. 2- a sole main canal is sufficient, which starts toward the ceht're of the ship, diverges on the two sides and branches into 13 and 14 in correspondence with the discs of the two screws.

In the ships with three screws, as shown in Figs. 3 and 6, the central screw does not work in the vortex. In Fig. 3 the central screw is placed as a continuance of the central bulge 18 which divides the two helicoidal canals.

In the case of Fig. 6, the helicoidal canals are united in a single canal 41 and the central screw is supported by the supporting arms 39 disposed in the center of canal 41.

For the ships with four screws two solutions may be adopted: the first one, schematically illustrated in Fig. 4, provides two main canals each of which branches off in two helicoidal canals. In the second solution the two helicoidal central canals derive from a single main central canal and the two lateral helicoidal canals derive singly from a pertinent main canal.

For the ships with five screws, two different solutions may be provided in order to have the greatest number of screws working in the vortical water and in this case there are four screws working in these conditions. The first solution is similar to that already shown for the ships with four screws (Fig. 4) and in this case on the prolongation of the partition of the main canals (Fig. 5) there is arranged the fifth screw working in non-vortical water.

The second solution (Fig. 8) is obtained by means of four canals (as in Fig. 7 in the case of four screws) two of which are provided laterally in the hull, 21 and 22, and two are central, 23 and 24.

Figs. 9, and ll show the application of the canal to the hull of a submarine.

In this case the hull is composed by a portion 25, continuously immersed and appearing on the surface in emersion only at stern, sharpened toward the bow and widened toward the stern and having a wing profile (Fig. 9).

In the central zone of said portion of the hull is provided the diverging canal 26 (Fig. 11) limited on its sides by the torpedo-shaped bodies 40 wherein the screw shafts are contained.

On the main hull there is placed a deck erection having a very fine horizontal profile 27, to give seaworthiness in emersion to the overall structure.

Fig. 12 shows a detail cross-section of a hull, perpendicular to the axis of the vortex, at the point where the water streams coming from inside of a canal join with those coming from outside the hull.

At 28 there has been shown the wall of a helicoidal canal, by 29 the external wall of the hull, by 30 the trace of the edge along which the two walls unite. The arrow 31 shows the direction of the vortex before entering the propeller, and arrow 60 the rotation direction of the propeller. 32 is the cross-section of a torpedoshaped body wherein the screw shaft is placed.

By assuming as a reference line the line 30-43 connecting the trace of the edge 30 with the centre of the screw shaft, the section of the liquid flow may be divided in four quadrants, in the sense of rotation of the vortex, by 33 has been shown the first quadrant, by 34 the second, by 35 the third and by 36 the fourth.

I claim:

1. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedo-shaped body which sharpens towards the stern, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped bodies toward the stem.

2. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedoshaped body which sharpens toward the stern, one propeller mounted on the end of each of said torpedoshaped bodies toward the stern, and a mantle in continuation of each of the said helicoidal canals beyond the said torpedo shaped bodies toward the stern.

3. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part'circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedoshaped body which sharpens toward the stern, one propeller mounted on the end of each of said torpedoshaped bodies toward the stern, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped bodies toward the stern, said propellers rotating in a direction opposite to the final direction of the said helicoidal canal, whereby the stream of water coming from the torpedo shaped body and entering the propeller reverses its direction of rotation in passing there through.

4. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedo-shaped body which sharpens toward the stern, one propeller mounted on the end of each of the said torpedo-shaped bodies toward the stern, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped bodies toward the stern, said propeller rotating in a direction opposite to the final direction of the said helicoidal canal, the wall of the latter ending before the said propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, said inclination being equal to that of the stream of water entering the disc of the propeller.

5. A ships hull as claimed in claim 4 further comprising a third propeller intermediate between the said two propellers mounted on the two torpedo shaped bodies, said third propeller being fixed to the hull by means of a support.

6. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedoshaped body which sharpens toward the stern, one propeller mounted on the end of each of the said torpedo shaped bodies, the axis of the said propeller being inclined with respect to the axis of the torpedo shaped body both laterally thereto and in a vertical plane, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped body toward the stern, said propeller rotating in a direction opposite to the final direction of the said helicoidal canals, the wall of the latter ending before the said propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, said inclination being equal to that of the stream of water entering the disc of the propeller.

7. A ships hull as claimed in claim 6, wherein the axis of each propeller is inclined with respect of the axis of amass the torpedo shaped body whereon it is mounted both lateraily thereto and in a vertical plane.

8. In a ships hull, a main central canal formed lengthwise in the. bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, a bulge formed in the bottom of the hull at the point wherein the said main central canal diverges in the said canals having an end portion with a helicoidal shape, the said bulge penetrating between the two helicoidal portions of the canals, the bottom of the hull at each of the said end portions assuming the form of a torpedo-shaped body which sharpens toward the stern, a propeller mounted on the end of each of the said torpedo shaped bodies, the axis of the said propeller being inclined with respect to the axis of the torpedo shaped body both laterally thereto and in a vertical plane, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped body toward the stern, the said propeller rotating in a direction opposite to the final direction of the said helicoidal canal, the wall of the latter ending before the propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, said inclination being equal to that of the stream of water entering the disc of the propeller.

9. A ships hull as claimed in claim 8, further comprising a third propeller mounted on the said bulge and projecting therefrom toward the stern.

10. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal inner shape, a bulge formed in the bottom of the hull at the point wherein the said main central canal diverges in the said helicoidal portions of the canals, the said bulge penetrating between the two helicoidal portions of the canals, the bottom of the hull at each of the said end portions assuming the form of a torpedo-shaped body which sharpens toward the stern, a propeller mounted on the end of each of the said torpedo shaped bodies, the axis or" the said propeller being inclined with respect to the axis of the torpedo shaped body both laterally thereto and in a vertical plane, a rudder mounted astern of the said bulge, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped body toward the stem, the said propeller rotating in a direction opposite to the final direction of the said helicoidal canal, the wall of the latter ending before the propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, said inclination being equal to that of the stream of water entering the disc of the propeller.

11. In a ships hull, a main central canal formed lengthwise in the bottom thereof beginning from midship, the

said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedoshaped body which sharpens toward the stern, a pro peller mounted on the end of each of the said torpedo shaped bodies, the axis of the said propeller being inclined with respect to the axis of the torpedo shaped body both laterally thereto and in a vertical plane, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped body toward the stern, the said propeller rotating in a direction opposite to the final direction of the said helicoidal canal, the wall of the latter ending before the propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, the outer wall of the said mantle forming with the wall of the stern plating an edge.

12. A submarine hull having a main central canal .6 formed lengthwise in the bottom thereof beginning from midship, the said canal having a p rt-circular; section which increases continuously in epthoward the stern until it forksto provide two canals, each of which has an end ortion with a helicoidal shape, the bottom of the-hull at each of the said end portions assuming the form or a torpedo-shaped body which. sharpens toward the stem, a propeller mounted on the endof each of the said torpedo shaped bodies,'the axis or the said propeller being inclined with respect to the axis of the said torpedo shaped body both laterally thereto and in a verticalplane, and a mantle in continuance of each of the said helicoidal canals beyond the said torpedo shaped body toward the stern; theisaid propeller rotating in a direction opposite to the final direction of the said helicoidal end portion of the canal, the wall of the latter ending before the propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, the said inclination being equal to that of the stream of water entering the disc of the propeller.

13. A four-screwed ships hull having a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with helicoidal shape, the bottom of the hull at each of the said end portions assuming the form of a torpedo-shaped body which sharpens toward the stern, two other canals disposed laterally to the said main central canal and formed in the zone of the planking which connects the bottom to the side of the hull, each of the said lateral canals having a part-circular section which increases continuously in depth toward the stern until it merges into a canal having an end portion with a helicoidal shape, the bottom of the hull at the said helicoidal end portions assuming the form of a torpedo-shaped body which sharpens toward the stern, a propeller mounted on the end of each of the said four torpedo shaped bodies, the axis of the said propeller being inclined with respect to the axis of the torpedo shaped body both laterally thereto and in a vertical plane, and a mantle in continuance of each of the said four helicoidal canals beyond the said torpedo shaped bodies toward the stern, said propeller rotating in a direction opposite to the final direction of the said helicoidal canal, the wall of the latter ending before the propeller in the form of a blade which is inclined with respect to the longitudinal axis of the hull, the said inclination being equal to that of the stream of water entering the disc of the propeller.

14. A five-screwed ships hull having a main central canal formed lengthwise in the bottom thereof beginning from midship, the said canal having a part-circular section which increases continuously in depth toward the stern until it forks to provide two canals, each of which has an end portion with a helicoidal shape, the bottom of the hull at each of the said helicoidal end portions assuming the form of a torpedo-shaped body which sharpens toward the stern, two other. canals disposed laterally to the said main central canal and formed in the zone of the planking which connects the bottom to the side of the hull, each of the said lateral canals having a partcircular section which increases continuously in depth toward the stern until it merges into a canal having an end portion with a helicoidal shape, the bottom of the hull at the helicoidal end portions last mentioned assuming the form of a torpedo-shaped body which sharpens toward the stern, a propeller mounted on the end of each of the said four torpedo shaped bodies, the axis of the said propeller being inclined with respect to the axis of the torpedo shaped body both laterally and in a vertical plane, and a mantle in continuance of each of the said four helicoidal end portions of the canals beyond the said torpedo shaped bodies toward the stern, said proller rotating in a direction opposite to the final direction of the helicoidal end portion of canal associated to the propeller, the Wall References Cited in the file of this patent UNITED STATES PATENTS 445,345 Hodgetts Jan. 27, 1891 1,034,626 Von Koppen Aug. 6, 1912 1,346,279 Tarn July 13, 1920 1,439,153 Davis Dec. 19, 1922 8 Hass Apr. 13, 1926 Kort Feb. 11, 1936 Yourkevitch Aug. 16, 1938 Mueller Dec. 26, 1939 Carlotti Aug. 14, 1951 FOREIGN PATENTS Great Britain of 1900 Great Britain of 1897 Germany Feb. 17, 1934 Germany Aug. 30, 1934 Germany Jan. 12, 1938 

